Evaluation of Silicon Neutron Resonance Parameters in the Energy Range Thermal to 1800 keV

Derrien, H.

doi:10.2172/814166

Cited by 7 publications

(5 citation statements)

References 14 publications

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“…The obtained average resonance parameters in this work are in good agreement with the last 232 Th evaluation in the RRR [27]. They can be used for calculation of average cross sections as well as of self-shielding factor.…”

Section: Discussionsupporting

confidence: 82%

Cross section structure of²³²Th in the unresolved resonance region

Koyumdjieva¹,

Janeva²,

Luk'yanov³

2010

J. Phys. G: Nucl. Part. Phys.

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An analysis of the 232Th neutron total and neutron capture cross sections has been performed in the energy region between 4 keV and 140 keV. The experimental data are analysed in terms of average resonance parameters utilizing a new statistical method for modelling of the resonance cross section structure in the region of experimentally unresolved resonances. The method exploits the characteristic function of the R-matrix elements distribution in Wigner's theory of nuclear reactions. To improve the representation of the 232Th cross section, the neutron strength functions for s- and p-waves are fitted to the experimental data in order to reproduce their observable fluctuations in (4–140) keV. Our method offers analytical expressions even for nonlinear functionals (observables) of neutron cross section as a transmission ratio. These functionals are incorporated into the evaluation process as a simple benchmark test for verification of the 232Th resonance parameters.

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Section: Discussionsupporting

confidence: 82%

Cross section structure of²³²Th in the unresolved resonance region

Koyumdjieva¹,

Janeva²,

Luk'yanov³

2010

J. Phys. G: Nucl. Part. Phys.

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“…In the resolved resonance region, a Reich-Moore evaluation was performed [202] in the energy range from 0 to 4 keV using the code SAMMY. Because the fission cross section is negligible below 4 keV, each resonance of 232 Th in the Reich-Moore formalism is described by only three parameters: the resonance energy E 0 , the gamma width Γ γ , and the neutron width Γ n .…”

Section: New Evaluationsmentioning

confidence: 99%

ENDF/B-VII.0: Next Generation Evaluated Nuclear Data Library for Nuclear Science and Technology

Chadwick

Obložinský

Herman

et al. 2006

Nuclear Data Sheets

1,962

908

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We describe the next generation general purpose Evaluated Nuclear Data File, ENDF/B-VII.0, of recommended nuclear data for advanced nuclear science and technology applications. The library, released by the U.S. Cross Section Evaluation Working Group (CSEWG) in December 2006, contains data primarily for reactions with incident neutrons, protons, and photons on almost 400 isotopes. The new evaluations are based on both experimental data and nuclear reaction theory predictions.The principal advances over the previous ENDF/B-VI library are the following: (1) New cross sections for U, Pu, Th, Np and Am actinide isotopes, with improved performance in integral validation criticality and neutron transmission benchmark tests; (2) More precise standard cross sections for neutron reactions on H, 6 Li, 10 B, Au and for 235,238 U fission, developed by a collaboration with the IAEA and the OECD/NEA Working Party on Evaluation Cooperation (WPEC); (3) Improved thermal neutron scattering; (4) An extensive set of neutron cross sections on fission products developed through a WPEC collaboration; (5) A large suite of photonuclear reactions; (6) Extension of many neutron-and proton-induced reactions up to an energy of 150 MeV; (7) Many new light nucleus neutron and proton reactions; (8) Post-fission beta-delayed photon decay spectra; (9) New radioactive decay data; and (10) New methods developed to provide uncertainties and covariances, together with covariance evaluations for some sample cases.The paper provides an overview of this library, consisting of 14 sublibraries in the same, ENDF-6 format, as the earlier ENDF/B-VI library. We describe each of the 14 sublibraries, focusing on neutron reactions. Extensive validation, using radiation transport codes to simulate measured critical assemblies, show major improvements: (a) The long-standing underprediction of low enriched U thermal assemblies is removed; (b) The 238 U, 208 Pb, and 9 Be reflector biases in fast systems are largely removed; (c) ENDF/B-VI.8 good agreement for simulations of highly enriched uranium assemblies is preserved; (d) The underprediction of fast criticality of 233,235 U and 239 Pu assemblies is removed; and (e) The intermediate spectrum critical assemblies are predicted more accurately.We anticipate that the new library will play an important role in nuclear technology applications, including transport simulations supporting national security, nonproliferation, advanced reactor and fuel cycle concepts, criticality safety, medicine, space applications, nuclear astrophysics, and nuclear physics facility design. The ENDF/B-VII.0 library is archived at the National Nuclear Data Center,

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“…Since the contribution from the interference term approximately cancels out, the result of integration is similar to the capture kernel and reads [1] (see p.72, Eq.3.3) 21) where the cross section is restricted to the resonance term, σ res n (E). The average scattering cross section in sufficiently broad energy group of the width ∆E = E 1 − E 2 around the resonance energy E 0 can thus be obtained as 22) which is the sum of potential scattering and resonance scattering, 23) with the resonance term being similar to the expression for the average capture cross section.…”

Section: Low Energy Approximationmentioning

confidence: 99%

Formalism for neutron cross section covariances in the resonance region using kernel approximation

Obložinský¹,

Cho²

2010

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We describe analytical formalism for estimating neutron radiative capture and elastic scattering cross section covariances in the resolved resonance region. We use capture and scattering kernels as the starting point and show how to get average cross sections in broader energy bins, derive analytical expressions for cross section sensitivities, and deduce cross section covariances from the resonance parameter uncertainties in the recently published Atlas of Neutron Resonances. The formalism elucidates the role of resonance parameter correlations which become important if several strong resonances are located in one energy group. Importance of potential scattering uncertainty as well as correlation between potential scattering and resonance scattering is also examined. Practical application of the formalism is illustrated on 55 Mn(n,γ) and 55 Mn(n,el).

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Evaluation of Silicon Neutron Resonance Parameters in the Energy Range Thermal to 1800 keV

Cited by 7 publications

References 14 publications

Cross section structure of²³²Th in the unresolved resonance region

Cross section structure of²³²Th in the unresolved resonance region

ENDF/B-VII.0: Next Generation Evaluated Nuclear Data Library for Nuclear Science and Technology

Formalism for neutron cross section covariances in the resonance region using kernel approximation

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Evaluation of Silicon Neutron Resonance Parameters in the Energy Range Thermal to 1800 keV

Cited by 7 publications

References 14 publications

Cross section structure of232Th in the unresolved resonance region

Cross section structure of232Th in the unresolved resonance region

ENDF/B-VII.0: Next Generation Evaluated Nuclear Data Library for Nuclear Science and Technology

Formalism for neutron cross section covariances in the resonance region using kernel approximation

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Product

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Cross section structure of²³²Th in the unresolved resonance region

Cross section structure of²³²Th in the unresolved resonance region